Electronics packaging involves providing electrical and mechanical connections, as well as providing protection, to, for example, a semiconductor chip. This field has been developing, and substantially started with metal or plastic based compound material packaging configurations.
Having specific regard to thermal management, packaging designs have improved over time for the removal of waste heat generated by the electronic devices. Typically, an electronic device for example, a semiconductor device, can fail when its junction temperature exceeds a certain threshold. The increasing power consumption trends of contemporary semiconductor devices can require sophisticated packaging that can handle large thermal loads. Some of the semiconductor chips commercially available today, require packaging which can dissipate waste heat at about 100 W per device. Light-emitting diodes (LEDs) can be included in this category.
Presently, heat pipes, thermosyphons, liquid coolers and other techniques, for example, are used in power electronics or digital processors to spread the heat load over a large area for dissipation of this heat to the environment, or transfer of the heat to an alternate location where free or forced flow of gas or liquid can enhance heat dissipation. Typically, traditional electronic device packaging is interfaced to a heat pipe or heat transfer system, by attaching the evaporator end of the heat transfer system to the outside of the packaging, as illustrated in FIG. 1. Generally, this technique provides an adequate but not optimal thermal interface to move and spread the heat generated by the electronic devices. This technique does however, allow for relatively inexpensive manufacturing of the package, as standard packaging processes and standard equipment can be used.
A downfall of current thermal solutions is that there is an undesirable thermal resistance that exists between the package and the thermal management system, for example a heat pipe. This fact can result in an increase in the junction temperature of the semiconductor material or electronic devices, thereby resulting in reduced performance and a possible shorter lifetime thereof. With further reference to FIG. 1, an elevated side view of an assembly of a light emitting diode package and a heat pipe 30 as is known in the art is illustrated. The light emitting diode package comprises a number of light-emitting diodes 40 which are affixed to and in thermal contact with a substrate 20. The substrate is in thermal contact with a carrier or a housing 10 which is in thermal contact with the heat pipe. This package design has to conduct heat from the light-emitting diodes 40 to the heat pipe 30, however, minute changes in manufacturing or assembly tolerances can compromise heat transfer across the interfaces between the light-emitting diodes, the substrate, the carrier or housing, and the heat pipe. As such, the overall heat transfer capability, mostly through heat conduction is typically suboptimal.
U.S. Pat. No. 5,355,942 discloses a method and apparatus for cooling a multi-chip module using heat pipes. The semiconductor chips are dispose into the multi-chip module through cavities in the module substrate, wherein the semiconductor chips engage the embedded heat pipes. This multi-chip module design includes a number of speciality requirements, including the creation of cavities within and along the length of the substrate, wherein it may not be possible to manufacture this requirement during standard electronic device package manufacturing.
U.S. Patent Application Publication No. 2005/0231983 discloses an apparatus comprising at least one heat pipe wherein each heat pipe has a first end and a second end and a cavity extending from the first end to the second end and a light emitting device mounted to and contacting the first end of each heat pipe. The light emitting device attach being mounted directly onto the heat pipe and such that the mounting configuration is free from any intervening substrate between the light emitting device and heat pipe. As the light emitting device is mounted directly onto the heat pipe, the pipe would progress with any package through the entire manufacturing process thereof. Therefore the size of the heat pipe would be directly impacted by standard package manufacturing machinery, thereby potentially limiting the effectiveness of the heat extraction capability of the heat pipe.
Therefore there is a need for a new packaging design that can be assembled using standard package manufacturing techniques while additionally providing a desired level of thermal transmission from the package to a thermal management system associated with the package.
This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.